I Loved You at your Darkest
by Shienhui
Summary: 'I remember the blood on my skin and his beating heart in my palm. I remember how it felt to end someone's life with my bare hands. I killed Father Fujimoto, my mentor, the Paladin and Rin's beloved dad.' Consumed by guilt, Mephisto helps Kaira by offering a teaching position in the Exwires. Little did she know that she would have to face Rin and the awkwardness that comes with it
1. Chapter 1

_Hey, Shienhui here! If you've read my other fanfics like Crossfire and Arrow, I want to apologize for not updating and I know I shouldn't be writing new ones before finishing the rest. But I just can't help it! I've suddenly got a spark of inspiration and I just had to do a BE fanfic. I'm thinking of shipping my OC with Rin and possibly a few others. Please review and tell me what you'd like to see in the future!_

 _Enjoy!_

 _I do not own Blue Exorcist, just my OC._

* * *

 **Chapter 1**

After what felt like an eternity, the school bell finally rang. I tapped my pencil against the table, my eyes glued on the piece of paper before me.

 _'Application for Teaching Assistant position'_

I swallowed. Throughout the last period of school, I had been rereading the letter that I wrote over and over again. My writing skills weren't perfect and to be honest the application letter didn't look too good either. But surely with Father Fujimoto and Neuhaus-sensei's recommendations, I would be accepted?

I hope.

 _Though I am an accomplished exorcist, I am still inexperienced when it comes to teaching._

A long sigh escaped my lips as I ran my fingers through my messy hair. If I do manage to become a teaching assistant for the new Exwires, I would not have to worry about next month's rent, or even the month after. Hell, I could even treat myself to a good dinner every night with that pay.

My stomach grumbled at the thought.

"Guess I'll be having instant ramen again tonight," I grumbled, rubbing my fingers against my cheek. "Seriously, I think all that junk food is making me ugly."

My eyes trailed around the now empty classroom, most of the students are probably either going home or cram school now. I guess I should send this letter to Mephisto and go back to my apartment. As I began to pack my bags, just then, glanced out of the window and to my surprise, there were Coal Tars everywhere.

I gasped. Those little black creatures filled the sky.

"What's going on?" I muttered to myself. It was faint, but I could sense a familiar demonic aura.

 _Could it be….?_

Immediately I dialed Father Fujimoto's number. I waited for him to pick up, but after a few rings, he still didn't. I left him a message and decided that I should check things out myself.

A rise in demonic activity such this could only mean one thing— a strong demon was on the loose, possibly causing some sort of rampage. Though I was off my exorcist duties today, I couldn't help but want to investigate. With curiosity getting the better of me, I rushed back to my apartment (which was thankfully) not too far away from True Cross Academy to get my exorcist gear. As I got out of the school building, I realised the severity of the situation. The Coal Tars had engulfed the entire school area.

It took me a while, but eventually I reached my room and retrieved my Tantos which were stashed under my bed. I did not bother wearing my exorcist coat considering I was off duty and also because it has been terribly hot for the past few days. Strapping both my Tantos onto my belt over my school uniform, I could feel the adrenaline pumping into my veins. It has been a while since I drew these swords.

With that, I left my apartment and out to the streets. Looking around, my gaze landed on a particular area of the town, not too far away from here, where the Coal tars were so concentrated that they reached up to the sky.

Bingo.

It took me about a good 10 minutes dash before I reached the source. My feet had brought me to some deserted alley. Even from afar, I could sense an overwhelming demonic power. Whatever was in there, wasn't any small fry—I could tell. I had to be prepared, or I'll just be running to my death. I had a few bottles of grade A holy water strapped against my belt. But I doubt they'll do much against a demon like this.

Slowly and quietly, I made my way inside. Both my hands were on the hilts of my blades.

As I got closer, after making a few turns inside, I heard voices followed by some grunts. My feet brought me to an open area, where there were a few boys surrounding familiar boy—

The brunette boy was pushed down onto his knees by some delinquents.

Wait. Is that _Rin_?

My eyes widened as I realized that it really was him. His face was twisted in pain and he had one arm clutching his stomach.

 _Were they bullying him? I have to stop them…!_

Without a second thought I said, "Stop it!"

My voice pierced the silence in the air and immediately all eyes were on me.

"Huhhh? What do you want, girl?" One of the delinquents sneered.

"Let him go. NOW." I said, more sternly this time.

"Bitch, you should leave unless you wanna get hurt."

"I should say the same to you, you fucktards." I growled, earning glares from them.

Rin merely looked at me wide eyed, as if I've grown another head. He shook his head lightly but dared not say anything.

Just then the grey haired boy stepped out towards me. His gaze drifted between my face and my blades.

I wasn't certain before, but I am now—that the strong aura from before was emitted by this boy. He was being possessed by a strong demon. His bloodshot eyes and dilated pupils confirms my suspicions.

The boy then said, "Hold him down. Make sure he doesn't escape. I'll deal with her."

"W-wait...you're going to fight a girl?" One of his lackeys said, mouth wide open.

The possessed alpha male smirked as he walked towards me. "Trust me. She's no ordinary girl."

Everything happened so fast. The next thing I knew, I was slammed against the wall with my arms pinned up above my head. Air was knocked out my lungs. As I desperately gasped for air, a waft of bad breath invaded my nostrils. I gagged.

"I suppose you know what I am?" His face was so close to mine and the tone of his voice was almost seductive. I felt myself blush.

"It's obvious from all the Coal tars that some demon lord is running lose. And of course, your breath smells as bad as ever. But I'd never expected it to be you, Astharoth. So what made you come all the way to Assiah?" I said with a smirk.

"I'd thought you'd remember me. Well, I'm here to retrieve my young master. Father wants him back in Gehanna."

"I'm afraid I can't allow that. I'm supposed to babysit him. So if you want to take him away, you will have to kill me first." I lied about babysitting him. But there was no way I'm letting him take Rin away.

"I see you haven't changed. As stubborn as always, my little Kaira~" he said in a sickening sweet tone.

"It'll be a shame if you die now. After all, there aren't many of your kind left." He said, his hand running through my silver locks. "To be honest. If I recall correctly, you're the last female of your bloodline. It's a shame that your rare blood is tainted by a human's."

"Shut up. I don't know what you're talking about."

One of his hands trailed up from my shoulders to my neck, as if searching for something. His hand stopped at the base of the back of my neck.

"Ah there it is. A demon seal. No wonder I can't sense your presence before….I can destroy that seal, you know and everyone will see how ugly you really are."

The tip of his nail dug into my neck.

But before he could pierce the skin, I drew my blade and pushed him off me. He stumbled for a moment.

"Leave that poor kid and fight in your true form." I said, pointing the tip of my blade between his eyes.

"Unfortunately I've become attached to this vessel. I don't want to give it up that quickly." He said as his eyes gleamed red. Ram horns protruded from his temples and his hands turned into claws.

I clicked my tongue in irritation.

"Hey. You punks!" I called out. But my eyes never left Astaroth.

"Ehh…..?" The boys were dumbfounded. Not that I blamed them.

"Release the boy and leave this place. Or I'll kill all of you."

"No don't let him go!" Astaroth growled.

"B-but, Shiratori….if we don't. ….."

I placed my second blade against his neck.

"If he dies, you die." I said, with a smirk on his face.

"You won't kill him." His grin grew wider, as if taunting me.

"How would you know?" I asked, smirking. "I wouldn't mind making the boy a sacrifice if I could kill a Demon Prince."

"Your pretty little lies aren't enough to fool me, you whore."

A flash of anger passed my eyes. "You do know that I could decapitate you anytime now? Know your place."

He growled.

Before I could retort, just then, all of a sudden, there was a burst of blue flames, and I was thrown against Astharoth. My blades slipped from his neck.

Barely recovered, I screamed for Rin to run away.

However, Rin was still dumbfounded of what had just transpired. Captivated by the blue flames in his palms, he failed to notice Astaroth approaching him.

"Oh….? The blue flames are the proof of Satan's offspring. So I wasn't mistaken after all…" The demon let out a deep, cruel laugh. He extended a hand to the younger male. "My name is Astharoth. Shall I take you with me, young master? Lord Satan is waiting for you—

"Shut up….! Rin, just run! I can't hold him back much longer…!"

As if broken out of a trance, he quickly made a mad dash out of the alley.

Astaroth's actions were immediate, as he pushed the blades away with his claws. Blood spilled from his palms. I swung my blade at him, but he easily deflected the attack with his claw. I thrust again. This time, the blade nicked the side of his torso and drew blood. He evaded a few more slashes before he broke into a run.

"Come back here!" I growled as I ran after the demon, only to be stopped by the sudden appearance of a figure before me. Clothed in a black robe, the man also had grey hair.

"Fujimoto-san!"

"Hey, kid. I'll take care of this guy. Do you mind going after Rin? He's probably wetting himself right now." The Priest said coolly.

I snorted. "Leave it to me…! Be careful, the boy is being possessed by Astaroth. "

"Got it. Bring him to a safe place!"

I sheathed both my blades and ran out of the alley. Surprisingly Astaroth did not stop me. With adrenaline pumping through my veins, I ran down the street in search of a boy in a blue hoodie. It took me a while, but eventually, I caught sight of him not far away. He was panting with his hand on his chest. Another hand was against the brick wall, trying to support himself. I could tell from afar that his legs were trembling. 

Not surprising, considering what he had just been through.

"Rin.…!" I called out, startling him.

He whipped his head around to see me, eyes wide with fear. "Who are you?! What do you want…?!"

"I need to get you somewhere safe before the demons come after you. Come on..!" I said, grabbing his arm, leading him into an alley. He was hesitant to follow at first, but soon later, he's running after me.

"W-what do you mean by demons?"

"I'll explain it to you later. For now, just run. Something is chasing us."

He made a wrong move to turn around to look because, the next thing he knew, he crashed into a garbage bin.

"Damnit. Get up!" I dashed in front of him, whipping my blades at the Naberius which was following us. The horrible stench from the corpse soon invaded my nostrils, causing me to gag. As the dead dog charged, I rushed forward, slicing it apart. But soon one came after another and I continuously had to put them down.

Tch. These small fries were starting to annoy me. It wasn't surprising, considering they were all drawn to Rin's newly awakened powers.

I released a small burst of demonic energy and sprang forward, killing all of them at a blink of an eye.

"Rin, let's go…!" I said, pulling his wrist and dragging him all the way till we reached the monastery. We came across a few demons, but eventually we managed to get there unharmed.

"Paladin Fujimoto is on the way…! Put up the protective barriers and douse the sewers with holy water! The demons are coming…!" I ordered the rest of the exorcists outside the monastery. They all obliged without question. I then turned to face Rin who was sitting on the ground, bewildered with the whole situation. I wouldn't blame him. Anyone would be shocked if they were assaulted by things which were supposed to exist only in myths and legends.

I extended my hand out to him. With a smile, I said, "Let's get you inside shall we?"

Different emotions flashed across his eyes at once. Confusion soon turned into anger.

Slapping my hand away, he then shouted at me, "W-WHO ARE YOU…?! WHAT'S GOING ON AROUND HERE…?! I-I don't know what's going on anymore…."

His voice trailed off. His head hung low, refusing to meet my eyes.

I knelt down in front of him. "Rin Okumura," I said.

Hesitantly, he looked up to meet my gaze. I reached out for his hand and rubbed circles over his palm, trying to sooth him. His sapphire eyes widened in recognition. I used to do this to calm him down when he was younger. He couldn't get along very well with the other children and from time to time he would get into fights. It was difficult to calm him down when he was angry—I guess it is because of his demon blood. Most demons have a trait for being hot blooded and violent.

Rin used to be really close to me. Whenever Fujimoto has to go on missions or train Yukio, I would babysit Rin. I would tell him stories and play with him all the time. Sometimes we would even take naps together.

"You're…!"

"Do you remember…? I took care of you when you were a small boy," I said, with a small chuckle. "It's been many years now and I didn't think you would remember. But I'm glad you did."

His shoulders relaxed a little but his fingers still trembled in my hand.

"I don't remember much…just a little…," His voice trailed off for a moment. Just then, his hand flew to grasp my wrist in a tight hold. "But of all times….WHY NOW?! You and dad, both of you were hiding this from me, weren't you….?!"

"Rin…"

"Stop calling my name…! I barely even know you—

Just then, shrieks pierced the air. Dozens of demons were trying to break through the barrier, only to be repelled back by a force. This wasn't good. Swarms of demons were coming this way and there is no way the barrier is going hold all of them off.iHHd

I pursed my lips. There was nothing I could do now but await for the Paladin's orders. Myself, alone could never take down that many demons at once.

Immediately, I pulled Rin up. "Get inside. It's not safe outside anymore. The demons could break the barrier anytime soon."

Reluctantly he obeyed and followed me inside.

"These demons are after me, aren't they? But why…..?"

I understood the severity of the situation but still, it was not my place to answer this question. Only Paladin Fujimoto could tell him the truth—that he was the son of Satan. I could only imagine how he would react to this.

A frown made its way to my face as I clutched the hilt of my sword tightly.

Those questions were left unanswered until Fujimoto got back.

The banging against the door got louder and louder. I cringe whenever I hear Rin's shouting. It was for his best, I kept telling myself. We just have to keep him in a safe place until we get rid of Astharoth.

Fujimoto had locked Rin in a small room, as we prepared to fight against the demons.

I bit my finger, drawing blood on a small tattoo on my wrist. "Inugami," I called out my familiar. The whole room engulfed with white smoke. Soon, a dog spirit became visible as it glided around the air. Its semi-transparent body was circular and almost about fifty foot long, resembling the body of a giant snake or dragon. With the head of a dog, it bore dark crimson eyes and rows of sharp teeth, looking as vicious as always.

"Looks like your little pup is ready," Fujimoto said, forcing out a grin.

"I bet he is. Right, Inugami?" I asked, looking up to him as he flew around.

He responded with a loud howl which echoed throughout the room.

"Blood thirsty as always," Fujimoto said.

Before I could say anything, a loud crash resounded outside and a split second later, the front doors of the monastery fell over with a loud tremor. Astharoth had rammed the truck he was driving through the gates and now the doors. The barrier keeping the demons back had been broken and now the demons were pouring in.

"Inugami, I'll deal with the King. You take out the rest of the demons. Make sure they don't get inside." I said, flicking my wrist at him. He growled in response, baring his fangs. With incredible speed, he shot forward, past Astharoth and out of the building.

"Stupid mutt." The demon growled.

Though Inugami could stop the demons from entering through the broken barrier, there was no stopping the demonic fungi which were growing rapidly around Astharoth.

He then turned to face me and Fujimoto. "Hand over the young master now…..!"

"We'll never hand him over to the like of you….!" Fujimoto roared, sprinting ahead.

I followed in suit, drawing both my tantos once more. The mark on my neck started to heat up and I felt a surge of energy to my limbs. When I got close enough, I sprang forward and slashed at the demon. He dodged it and disappeared, before reappearing behind me.

I spun around to parry his attack. His claws had an iron grip on my blades. Considering he was a demon king, his strength was unimaginable and it didn't take long for him to push me down to my knees. My hands trembled as he continues to press the blades down.

Sweat trailed down my forehead and my face started to grew warm. I barely had any strength left and my muscles were aching. My eyes darted left and then right. The rest of the exorcists were preoccupied with the rest of the demons to even spare a glance at me.

"Aww what's wrong….? Giving up already…?" He sneered.

Just then, gun shots rang the air and Astharoth staggered after having shot multiple times. Taking this opportunity, I kicked out his legs causing him to falter back. My weapon was released and I quickly got to my feet. But before I could attack, I was thrown onto the ground. Head colliding with the hardwood floor, I was in daze. His claw dove down and penetrated through my abdomen. Blood spilled and I found myself paralyzed on the ground.

"Well this is disappointing. I thought you would put up much more of a fight, Kaira. But I guess, it's too late now. You're dead—

Before he could finish his words, a pitch fork zipped through the air and penetrated him, knocking him down to the ground.

"Like I said, we are not done talking yet, you old fart!" Rin shouted at Fujimoto. So he was the one who threw the pitch fork.

 _Not bad Rin._

I tried to smile. But the pain in my stomach reminded me of the severity of my wound. Even with my healing abilities, this wound would take hours if not a few days to completely heal. Right now, I can't even move my body.

Fujimoto by now had completed reciting the fatal verse. With a loud cry, the demon finally left the boy's body. The priest then proceeded to give instructions to the rest of the exorcists before giving me a look. I gave him a reassuring smile and a weak nod.

"Rin, we have to get you into hiding now. It's not safe here." Fujimoto said.

"Wait. But shouldn't you take care of Kaira first…?!"

"The rest of the exorcists will bring her to the hospital. Right now our first and only priority is to get you into hiding. Don't ever forget that it's YOU that demons are coming after, Rin."

"Is that right?" Rin's voice grew bitter. "So what you're saying is that everything will be fine if I'm gone."

"No, Rin!"

"Fine. I'll be happy to leave. You'll feel a lot better if I did anyways."

"Rin….!"

"LET GO…! You're the one who wants to kick me out of here. You don't have to tell me that I'm the screwed up son! Actually, we're not actually related! So I'm the screwed up STRANGER, right?!"

"Stop it!"

"Come on, why don't you admit it…?! You're just sick and tired of pretending to be my family. Or is it against your religion to say something like that? OR WAIT. Do you want to play one last time as the perfect dad?! Give me a break. You're not my father. You're nobody to me. Don't ever let me see you acting like my father ever again—

Rin was cut short by a slap on the face. At least, that's what I thought I heard.

There was a silent pause for a moment.

That was, until Fujimoto broke it. "It'll be morning soon. Go get your things."

 _"….yeah…..okay…"_ Rin said in a low whisper.

No matter how much I craned my neck, I still can't see what was happening. I wanted to say something, but the words were caught in my throat. The bleeding had stopped. However, the agonizing pain in my abdomen has yet to reside.

All of a sudden, I heard a loud thud, following a groan from Fujimoto.

"….Old man….?"

"Father Fujimoto….?!" I called.

"Don't you dare come a step closer….!" Fujimoto shouted for all of us to hear.

 _What's happening….?_

I knew something was amiss. Despite the pain, I forced myself to my knees to take a good look. Fujimoto was on his knees and his hand was clutching his chest.

All of the lights exploded suddenly, leaving us in a shroud of darkness.

"….hahah,…hhahaahahhahhahaha…..! At long last, I've claimed this body as my own…!" A new, sinister voice had replaced Fujimoto's.

My eyes widened in realization.

 _Shit. No….!This can't be happening…!_

"Everyone get away…! He's been possessed by Satan…!" I screamed. "Get away from him, Rin…!"

The possessed Fujimoto looked up to see the boy, with a Cheshire grin spread across his lips. "Well, finally we meet, my dear son…Hhahahahahahhahaha…..!"

As if on cue, bright blue flames burst out of his body. His shoulders shook as he roared with laughter.

Rin fell back in shock, as he stared wide eyed at the man. Fujimoto's teeth became fangs, pupils became slits and his tongue became abnormally long. His ears also became pointed. He was fully possessed by the king of hell.

"Hey there, son! Doin' good?" He pointed at pale faced Rin. "That's right, the man himself has come all the way out here just to see his cute little boy! So look happy about it…!"

"Y-You're a demon…." Rin whispered.

I could tell that the boy was scared out of his wits. He was frozen on the ground and wasn't moving anytime soon.

"The name's Satan….God of demons and your one and only father. You can call me 'papa' if you like! Gyahahahhaha…!"

"Now then….I'd really like to stick around and savor this touching reunion…..but I'm thinking this guy's body isn't going to last too long, you know?"

Just then, the demon ripped out Fujimoto's fingers, earning a gasp from me and Rin. His gaze travelled down to me, possibly only realizing that I was here now. Grin widening, he waved his bloodied hand at me.

"Why hello there. I didn't notice you there." He said. Blood poured down from his wound to the wooden floorboards.

I cringed, when some of the blood splattered on my face.

 _"Bet you haven't eaten in a long time, huh? Here. You can chew on his fingers if you like…."_

Upon hearing those words, I narrowed my eyes at him. "Don't fuck with me." I screamed.

"Why are you mad? I'm just offering you some food. You can't starve yourself just **because you're trying to play human** , you know?"

"It's none of your damn business. Now get the fuck out of Father!"

He shook his head and chuckled in response. "You can't stop me."

A sickening crack resounded through the whole room and more blood poured out of his digits.

Something in my head clicked and I realized what he was doing. "No you don't….!" I screamed.

In a flash, I sprang up to my feet and was charging towards him. But before I could slash him, blue flames engulfed my body, searing me.

"AHHHHHHHH…!" I cried out, dropping both my weapons and falling to my knees. So this was the power that reigned over Gehannna. I'd never thought I would ever encounter such power. But as I thought, I was no match for it.

Still, I wasn't about to go down without a fight.

 _I had to protect Rin. That was what I swore I would do…._

* * *

 **Flashback**

 ** _12 years ago_**

 _"They're both adorable, aren't they…?"_

 _"Why do I have to babysit them…?! I'd rather be out hunting!" I said, with a displeased look on my face._

 _"I noticed your movements have become sluggish as of recent. You're overworking yourself. Look, even your shoulders are tense!" Fujimoto said, with a laugh as he ruffled my hair._

 _"I'm perfectly fine!"_

 _"No you should take this week off….and let's not think of this as a break. Think of this as a task from me. I want you to protect and care for these two boys while I'm away."_

 _I crossed my arms, glaring at the priest._

 _He let out a long sigh. "Look…..I'll teach you how to strengthen your familiar with a summoning technique when I get back. How does that sound?"_

 _"Hmmm…." I placed my thumb on my lips, looking thoughtful. "You owe me some food too."_

 _"…What…?! You've been eating out of our fridge for weeks now…Isn't that enough..?"_

 _My glare on him intensified._

 _"F-Fine fine. I'll cook a good meal for everyone when I get back."_

 _I let out a small giggle. "That's good enough…Now….."_

 _My gaze wondered around the room to see twin boys playing with some stuffed animals._

 _"Rawr…!"_

 _"…ahhhh! Owwwww….that hurts..!"_

 _"Rawr rawr….!"_

 _I turned to Fujimoto and asked him, "What are their names…?"_

 _"The one with the tiger plush toy is Rin. The other is Yukio. Please be patient with them. They can get out of control sometimes, especially the older one." He said, nodding at the boy._

 _"RAWRRRR…!" Rin shouted as he threw the toy to Yukio's face, causing him to cry._

 _Oh no…_

 _While Yukio wailed, the other twin continued picking up other toys and scattering them around all over the room._

 _Sweat trailed down my forehead, while Fujimoto merely laughed nervously. I have absolutely no experience in taking care of children. Something in the back of my mind told me that this wouldn't end well._

 _With a sigh, I walked over to Yukio and knelt down in front of him. Immediately, he looked up at me questioningly with his tears still pouring. Placing my hand on his puffy cheeks, I wiped his tears away with my thumb._

 _"Yukio…come on don't cry. You're a big boy, right?" I asked with my hands on his shoulders._

 _Slowly, he nodded._

 _"Big boys are tough and cool…They don't cry," I said, smiling._

 _"Y-Yeah. I-I'm tough…..and I'm cool." The little boy said, wiping his tears away with the back of his hand, as if he was embarrassed._

 _"That's good, Yukio. You're going to grow up as a fine man."_

 _Blushing, he then went back to playing with his toy train._

 _My gaze then met Rin's. The next thing I knew, I was hit by a piece of lego square on the forehead. I tried not to curse in front of the children. Rubbing the sore spot, I knew it was going to leave a mark. I then glared at the older boy and he responded by sticking his tongue out at me._

 _"So you're the naughty one," I said as I ran after him. He laughed as I chased him around the room. Finally after a while, he got tired and his running came to a slow. Taking this opportunity, I swooped down to grab him and tickled him._

 _"This is payback…!" I said. Rin laughed uncontrollably and soon, I found myself laughing as well._

 _When I finally let him go, he gave me a pout._

 _"Can we play again?" He asked nicely, with a bright, cheerful smile on his face._

The smile which adorned his face was something that I could never forget. The more time I spent with the boys, the more I became drawn to them. After learning truth about Rin and Yukio's origin, I became more protective over them.

When the time comes, I knew one day that Satan might take Rin away.

* * *

"I just can't believe that day is today," I whispered to myself.

Gritting my teeth, I dragged my fingernail over the seal on back of my neck, just enough to draw blood. Immediately I felt a surge of energy within me. Whatever burns and wounds I had before immediately closed up and healed. My hands turned into sharp red claws which were as long as lances. The rest of my body remained unchanged. With the seal acting as a limiter to my powers, I could not complete my transformation.

"Oh hoh…! What a surprise….! You are a true demon after all." Satan crackled with laughter.

A soft growl escaped my lips.

His insidious grin merely widened as he started to spout strange words that I couldn't understand. He was casting some sort of spell.

I dashed forward to slash him with my claws. He dodged the first few strikes. Occasionally he would throw huge fireballs at me. Easily, with superior speed, I dodged them. When I went close enough, he would create a wall of flames to protect himself.

"What are you waiting for…? Are ya' hesitating?" He sneered.

I gritted my teeth.

"Someone with your caliber would be able to defeat me in this form. But you're scared aren't ya'? Too scared to butcher this old pops?"

Truth to be told, I was trying to buy some time. At least enough time for backup to come. Unfortunately, considering my demon heritage, I wasn't able to recite or even read any parts of the bible. The only way to cast Satan out of Fujimoto is by performing an exorcism that only high level Aria exorcists knew.

Without an Aria here, the only way to stop him was _to kill the Host_ , in this case its Fujimoto.

My claws trembled.

"You can't kill this old man, can you…?! Haahahahahahahahhahahahah…!"

On cue, a whirlwind of flames engulfed me. My claws blocked the flames just enough to protect myself. The rest of the room was turned into nothing but ashes.

My gaze shifted from the demon to Rin. I've never seen him this upset before. His eyes were pleading me—pleading me not kill his beloved father.

Another blast of flames was sent my way and once again, I blocked it.

"Awww….I'm getting tired of playing with ya'. It's time me and sonny boy 'ere go home to spend some quality time together. We have a lot of things to catch up on, right sonny?" The demon laughed. "I'm the only demon that could create this, the Gehenna Gate..!"

Before both me and Rin, the gate to the other world was opened on the ground.

"Now then, let's go. Gehenna's waiting...Oh wait. I have to destroy this, first…I'll release you from this irritating curse…!" He picked up Rin's sword, Kurikara and approached Rin. He grabbed him by the arm and proceeded to drag him towards the gate.

Frozen in place, I only stared.

"It's time for you to regain your true power as a demon!"

"Fuck off…!" Rin snarled and two small floating blue flames appeared above his head.

"Pffft….hahhaahha..! What do you call that?! Did you just piss your pants or something?! HAHAAHAHA!"

As I watched Satan berates Rin, my heart clenched. I bit my lip till I drew blood. They were already at the edge of gate and Rin's attempts to struggle were futile. Just one more push and Rin will be thrown into Gehanna.

 _I can't watch this…_

"I'm sorry, Rin. Please forgive me." I said as I extended my claws and drove them into Fujimoto's chest.


	2. Chapter 2

_Hey, how's everyone? Thank you for your reviews for the previous chapter! Here are some answers to some of your questions:_

 _1\. Yes, I include a mephistoxoc pairing in this story. But this would be more evident in the later chapters, due to the flow of the story. :D_

 _2\. Most of you probably noticed about the OC's age- yes, she's much older than Rin. She is about 300 years old (due her being half demon), which is equivalent to a human age 17-20 ish. :)_

 _Anyways, hope you enjoy this chapter!_

* * *

 **Chapter 2**

" _Her?! You mean SHE'S the one who killed Paladin Fujimoto…?!"_

" _Rumor has it that the Paladin was possessed by Satan."_

" _Wait how is it even possible in the first place?! There's no way the Paladin could be possessed."_

" _I'm telling you the truth! Makoto told me he saw the blue flames!"_

" _So she killed him with her bare hands, and then what—_

" _But to think she could stand up against Satan. She must be a demon herself."_

The noisy bickering from the group of exorcists stopped as I slammed my fists on the bar counter, glaring at them. Their faces immediately grew pale. Slowly one by one left the table, like frightened mice.

As I watched them leave, I cursed under my breath. "Seriously. It's been weeks now and they're still talking about it?"

The bartender narrowed his eyes at me. "Gonna scare off more of my customers, are ya'?" He asked, as he shook his head.

I narrowed my eyes at him and placed my hands on my hips.

"I'll take up more requests tonight to make it up to you." I said. A long sigh escaped my lips as I stared at the blood red wine in my glass. I could see my own tired reflection on the surface—there were dark circles under my eyes and my lips were paler than usual.

"There aren't any requests tonight, at least none which might interest you."

"Just give me anything. Like seriously….I don't mind going for the small fish. I just need to do something to get my mind off what happened."

"It's still bothering you, huh? How long are you going to mope around like this? What's done is done. There's no changing the past."

"I know….I know…Everybody tells me that."

"And god knows it's not your fault. You did what you have to do, so stop blaming yourself for everything. I can only imagine how difficult it must be for you."

"I'm not blaming myself." I said, downing down the whole glass of wine.

"But you certainly act like you are." A new voice piped in. Before I could turn around to retort, my whole face was slammed onto the table, by a hand on the back of my head.

"What have you gotten yourself into now, **brat**?"

The glass slid off my fingers to the ground, where it shattered into dozen of pieces.

I grasped my assaulter's wrist.

"Let go." I ordered.

"Whaaaatttt...? I can't hear you~" She said in a sing-song voice.

With all my strength, I pulled her wrist forward. She gasped, falling forward and her head collided with the counter top.

Finally, she released me and I got up to glare at her. Red hair and giant breasts greeted my sight immediately.

 _Well, well….why am I not surprised?_

"Owwww…..you're so rough, Kaira. There's going to be a bump on my head now." Shura said, rubbing her now sore forehead.

"Says you. You're the one who started this," I said, narrowing my eyes.

"You deserved it."

"Huhhh…?!" I hissed at her, ready to slam her onto the table again.

"Yeah…quit being so depressed already. I heard you've been on a killing streak ever since Fujimoto died. Bartender-san here has told me about everything…Girl, you should stop being so bloodthirsty."

I glared at the old bartender who gave me an amused smirk. "Mind you. Miss Shura here is one of my best regulars."

"Yeah…because she drinks her ass off till dawn every day." I snorted.

The red head's reaction was immediate. There was a sharp tug on my hair as she leaned her face close to mine. "What did you say?!" She shouted in my ear.

"You heard me. You're a drunk ass."

I got a painful flick on the forehead in response.

"Owww….That seriously hurt, woman!"

"Seriously. You have to take care of yourself more, Kaira. You have to accept that Fujimoto's gone now and that you've made the right choice."

"The right choice?! I killed him, Shura. I-I killed our mentor…..The Paladin. I killed R-Rin and Yukio's dad….!"

Shiro Fujimoto had meant so much to me. Not only was he my superior, he also used to be Shura's and my mentor. He was the reason I even became an exorcist in the first place. He accepted me for being a half-demon and gave me reason to live on.

"Pull yourself together!" She shouted at me, as she held my wrists. "Look. Your hands are shaking. You're scared aren't ya'?"

Indeed my hands were shaking. In fact, my whole body was trembling.

The memory of my blood stained hands were etched in my head. My claw had driven itself into  
Fujimoto's chest, piercing through his heart. Blood spurted everywhere—it was on my arms, my clothes and even my face. My whole body was dyed crimson. I remember seeing Rin's face morphing into one of horror. I remember seeing him go down to his knees, crying and morning for his dead father. All I could do was stare—stare at his dying form, unable to do anything. I was a failure as his student—a failure as an exorcist.

Just then, a rough push on my shoulder jolted me out of my train of memories. Shura led me out of the bar to a deserted alleyway nearby. When we were both alone, she turned to face me. Hands flew up to my shoulders as she started to speak.

"Kaira. Look at me. Fujimoto's death could not have been avoided and you know this. You should know the state of his body when he was possessed. The strain in his body would have killed him. No exorcist could survive being a vessel for a demon as strong as Satan."

Tear welled up in my eyes. I felt her hand pat my back, trying to comfort me.

"But you know….if it wasn't for you. Rin wouldn't be here with us right now. Have you thought of that?" She said, with a small sad smile.

Only silence left my lips.

"He's really worried about you, you know? So is Yukio. They both know that this isn't your fault. So don't be so hard on yourself."

"I don't think I can ever face them ever again."

Shura sighed. "You have to. At least try. You remember what we promised Fujimoto, right?"

My head was clearing up once again. A memory was starting form before my eyes.

* * *

 **Flashback**

" _You…..! Kaira…..! Both of you are in on this?!" Shura's voice bounced off the stone walls. "You have got to be kidding me."_

" _It's true. I've sealed his demon heart into Kurikara. It's the same sword which defeated the Impure King over a hundred years ago. Till now, Rin has lived a normal life as a human but one day, the sword will lose its ability to contain its power," Fujimoto said, crossing his arms._

" _I can't believe this! And the Vatican knows nothing of this?! You've been hiding Satan's son all this while?!"_

" _Yes. I know it's difficult to understand. But please…I know is selfish of me to request of this. But…if I were to die, I want you two to teach him how to control his powers. You're the only people who I can count on. Kaira, with your demonic bloodline, you're the only one who could relate to Rin. I want you to teach him how to control his flames when the time comes and to be his guardian in my place.….." There was a pause. "And Shura. I want you to guide him and teach him how to wield Kurikara. No one knows as much about Demon Swords as you."_

 _Shura's reaction was immediate, "Don't be ridiculous! You're going to throw your life away for the Son of Satan?!"_

"…"

" _What a bunch of bullshit!" With that, she stormed away, fuming. Before she left, she threw a glare at me. "And you…! I can't believe you're going to go along with this plan!"_

 _Fujimoto let out a heavy sigh as he watched her form disappear from sight. He then turned towards me and ruffled my hair._

" _You're pretty quiet, Kaira. Are you shocked?"_

" _A little. But I understand. I will teach him how to control his demon side and I'll protect him with my life." I said, trying to avoid eye contact._

 _ **If one day, Father Fujimoto does die. What will I do then?**_

 _ **Will I be strong enough to protect Rin?**_

 _He seemed taken aback by my words. A small smile soon crept up to his face. "You love Rin, don't you?"_

 _My eyes widened at his words. I could only stare at him quizzically._

" _I—love Rin?"_

" _I can tell. You really care a lot about him."_

Those words echoed in my head. I was brought back to reality when Shura brushed her hand on my shoulder.

* * *

"Yeah I remember." I said, my voice sounding a little brittle.

"Rin still needs you. You're the only one who can help him. You're his guardian now."

I began to sob as I buried my face in her shoulder. Her arms wrapped around me. Patting my back lightly, she tried to sooth me.

"Hey heyyy…..calm down…..I haven't seen you cry like this in a long time."

"That's because you're never here. Where have you been for the past few years?" I asked, trying to hold back the tears, but no avail.

"Since it's you, I'll tell ya'. I'm actually here as an Inspector for the Vatican."

"You're working with the Vatican?!" I gasped, about to pull away before she stopped me.

"Don't worry. You're secret's safe with me. I won't tell anyone about it."

Relief flooded through me. She gave me a little scare when I thought the Vatican knew about my existence. Considering that I'm a half demon, I had to keep my bloodline a secret from the Order as well as the Vatican. They'll execute me if they ever found out.

"Then why are you here?" I asked.

She merely smirked at me. "How about I tell you this another time? I'm getting reaaaallll sleepy now. Let's go home."

The side of my lips twitched. "Now you're making me curious."

"Seriously, it's no big deal. I'm just here to investigate some 'stuff'."

"Right…."

* * *

"We're going in from the back. Once we get close enough, we can ambush the demons. Dragoons, you act as a decoy to lure them in one place—

"We don't need a decoy! We can just attack all at once. There aren't that many of them." One of the male exorcists piped up.

"I agree. We don't need a decoy." Another male said.

"These beasts aren't as weak as they look. Trust me, it'll take much more than a few shots to kill them." I said.

"Seriously. Don't be such a worry wart. Let's go and kill them already." This time it was a girl.

" _Worry wart_? I'm your captain for goodness sake. What I'm doing is for all of your safety!" I reprimanded them, crossing my arms.

"To be honest, you don't deserve to be our captain. You don't deserve to be an exorcist after what you done to our Paladin! You're nothing but a murderer!"

"W—What?" Almost immediately, I felt the blood drain from my face.

 _A murderer….._

"Killing demons is no big deal for you. So I suppose that killing a human is no different, huh?"

"We all know you enjoy butchering demons. You kill them every night, don't you?"

"I guess you're finally showing your true colors. You're just no better than a blood thirsty demon."

Words were caught in my throat as my teammates continued to berate me. I knew I was at fault. I understood completely why they hated me—and it is not just for this single reason.

 **They knew I wasn't completely human.**

It was natural for humans to fear and hate people—beings different from them. At least, that is what I learned after living for centuries. Well, for approximately 300 years, even though I probably look no older than twenty. In the early years of my life, I've been shunned by the people around me and often, casted out from villages or towns. My body was of a child back then and I didn't have the strength to defend myself from the beatings the villagers have given me. Though my wounds heal quickly, they still hurt like hell.

 _I didn't choose to be born this way—I didn't chose to become a demon…._

But of course, the humans never understood that.

… _..and I don't think they ever will…_

"Maika, Sonjou, Akira, Rika, let's go. I'll lead the team from now on." My arrogant teammate said. With that, everyone agreed and left me behind. As I watched their fleeting forms, I fisted my hands, trying to stop them from trembling.

 _I guess this is how things are going to be from now on…_

 _I wonder how much of this I could take…..?_

 _For centuries I have been condemned by humans for my blood….so I should be used to this kind of treatment, right?_

… _ **but why does my chest still hurt?**_


	3. Chapter 3

_If you're wondering what Kaira's familiar looks like, check out the image in this link! Inugami is absolutely adorable~~! (hopefully you all agree or maybe I'm just weird hahaha). wiki/Inugami?file=478_-__

 _Anyways, remember to review! Please favourite/follow this story to show your support/motivate me to keep writing! :)_

 _Enjoy!_

* * *

 **Chapter 3**

After meeting Shura the other night, I haven't seen her again. Even though she gave me her cellphone number, she never picks up.

I bit my nail in frustration.

"Fine, if that woman doesn't want to pick up then I'll—

I stopped short when my phone in my hand suddenly vibrated. A growl escaped my lips when I saw the caller's name on the screen. For some reason, whenever I hear or see his name, I get ticked off.

 _Mephisto Pheles._

"What do you want?" I asked, in an irritated voice.

"My, someone got off at the wrong side of the bed this morning~!" His voice sounded almost screechy from the other side. Or maybe my ears have just forgotten how dreadful his voice could be.

"…"

"Fine, fine. I'll get straight to the point~! I've given a lot of time off for the past few weeks and I think it's time for you to get back to your job. What do you say?"

"To be honest, I'm tired of being your slave. I'm thinking of quitting…"

"WHATTT…?! YOU CAN'T QUIT~! Wait! Not that I've ever thought of you as a slave or anything. After all that I have done for you…I can't believe these were your true feelings all along!"

"Well….you made me do all those dirty work all the time…." I said, voice trailing off. Aside from Fujimoto, my loyalty also lies with Mephisto, considering I'm indebted to him for keeping my secret from the Vatican and Grigori. In return, aside from my exorcist duties, I have to deal with his requests as well. Most of the time those requests involve cleaning up after his chaotic green haired demon brother or making tea for him.

 _Honestly, I would prefer tea over the former._

"I did no such thing! All I did was give you some simple tasks here and there—

"SIMPLE?"

"Ah….maybe not that simple then…"

"…"

I was silent for a moment. Then I thought of something, and asked him, "….Samael…?"

"Hmmm…?"

I could tell that he perked up when I called him by his real name. I have known him for a long time now, even before I became an exorcist—and considering that we are both demons, it was natural for us to call each other by our real names.

 _Samael, the King of Time…_

I was born in Assiah from a human mother, but was abandoned after she found out I was a demon. Growing up had always been difficult for me. I was a cursed child who was often thrown out of villages—and was forced to starve on the streets. There were times when I was caged and tortured mercilessly, in the worst possible way. Because of those horrible experiences, I grew up to hate humans—and eventually exorcists.

That was until…I met _Mephisto_.

Initially, I didn't understand him. He was the second strongest of the Eight Demon Kings and yet, he chose to wander around Assiah, looking for the company of humans. With his power, he could take over the world—destroy all human life—yet, he chose to do the opposite. He chose to assist the Vatican and the Order. That was what I didn't understand about him. Humans and demons could never coexist—at least that was what I used to believe.

But that changed when he and Fujimoto took me into the Order. From there, I began to learn new things about the world—about humans which I never knew before. Soon, after years of being an exorcist, my hatred subsided.

Back then, Mephisto was the only demon I knew in True Cross, so often—even now, I found myself confiding him whenever I have problems.

"I was thinking…..is it possible if I resign my position as Captain from my team…?"

Immediately, from the gasped I heard at the other end of the line, I could tell he was shocked.

"W-Why would you do that…?! True Cross needs you….! You can't just leave like that—

"….I've been thinking about this for a while now. I think after what happened….this is the best choice for everyone." I said, letting out a long breath. With all these rumors going around, it'll be best for me to lay low until the excitement dies down.

Mephisto was silent for a moment. "…are your squad members giving you a hard time…?" For once, he seemed genuinely concerned—not the mock concern he always gives me.

I was hesitant, but after a while, I said, "Yes."

"I see…well….." There was a pause before he shouted over the phone.

"AHA~!"

In an instant, I recoiled from the headpiece. HE NEARLY BLEW UP MY EARDRUMS!

"Y-You…..! I could have gone deaf, you know!"

"Yeah—yeah—that's not the point." He said, ignoring me. "We are severely lacking staff in the teaching department. Would you like to be a teacher for the new Exwires?"

"W-wait….what…?"

"You heard me. I want YOU to be a teacher for the new Exwires!"

"T-This is too sudden…I need time to consider this…."

"Nonsense~! I know that you're perfectly suited for this job!"

"No seriously….I—

"Good! You will teach the class about Demonology."

"Oh right. Because I'm a demon, **woohooo** ," I said, voice full of sarcasm.

"Well that is sort of true~. No one has as much knowledge as you about demons—well at least, no one human…So this job would definitely suit you perfectly…!"

I groaned inwardly. As much as I hated to admit it, he DID have a point.

"What's the salary?"

"Ehhh…? It's the same as your previous salary…"

I cleared my throat.

"F-Fine, fine, fine, fine~! I'll give you a raise…! Sheesh…."

I smirked, giggling, "Thank you, Sir~ And when do I start?"

He grunted, probably sulking now. He is always upset when I ask him for a raise—well, it's not just me but he gets upset whenever money is involved.

"You start tomorrow."

"Wait what…?! Already?!"

"The term started two weeks ago and the Exwires hadn't had their Demonology class since. So you'll have to catch up on the syllabus they missed."

"Y—You cunning little—

"Ooohhh well, look at the time! I have to be on my way for a meeting. Best of luck on your new job, Kaira~! Toodles…!"

"H-Hey wait—

…and he hung up.

* * *

I woke up the next morning by a jolt of pain. Crying out in pain, I looked at my fingers which were now red with bite marks.

"Inugami…! That hurt!" I screamed at my familiar.

The dog spirit laughed in response, its beady red eyes widening in glee. Honestly, there was something wrong with this bloodthirsty, sadistic mutt.

"Oi. What did you do that for?!" I asked, glaring at its floating form.

"You'll be late if you don't get ready soon. KeEh…ekekeEHEHEeheheh….."

"But it's Saturday. I don't have classes today—

"You have a new job, remember? Or did you forget? KeHehHEHeheh….You must be getting old if you've forgotten about that…? Kekekeke…..!"

When I looked over at my alarm clock, my heart nearly leapt out.

"Shit…! Shit…! Shit! Why didn't you wake me up sooner?!"

"Kekeh…keh…keh…."

With a growl, I threw off my blankets and did a mad dash to the bathroom.

"Well whaddaya' know? I got here in time after all."

Inugami crackled a laughter. "I can't wait~kehehehh…!"

"You better not terrorize any of the students here." I hissed at him.

He grinned, all-knowingly and I narrowed my eyes in response.

* * *

"Anyways, where is the classroom…? It says here that it's in classroom 1106." I said, reading the teaching schedule I got from Mephisto.

Along the huge corridors were probably hundreds of doors, which all looked the same. To make matters more complicated, there were no number plates on any of them.

"Hah….looks like we're lost. Inugami, can you smell anything?"

"Kuehhehehe….Lucky you. There must only be one class today. I smell humans up ahead, five doors from here…"

"Okay then."

"KeheEHeHehheheheh…."

"What is it…?" I asked, glancing over to him, suspiciously.

Inugami merely soared in circles in response. He seemed excited—much too excited than usual. Not that he would tell me why. Ignoring him, I went ahead and opened the door to the classroom. As the door creaked open, my heart started thumping wildly for some unknown reason.

 _Was I that nervous?_

 _I have been to many exorcist missions, so teaching should not be any different, right?_

As I stepped inside, I was greeted with a close-to-empty class, save for a few girls sitting in the front and a group of boys at the back. The classroom was certainly not what I expected—it was quite unkempt with stacks of books and boxes everywhere. I guess this place hasn't been used in a while and I'm not surprised—it is because of the decline in the number of people applying to become exorcists.

"Is this the Exwires preparation class?" I asked, forcing a smile.

"Yes! Are you out new teacher…?" A girl with pigtails asked, her eyes gleaming with excitement. However, I soon realized her excitement wasn't directed at me, but at Inugami who was floating behind me.

"Hahaha….Yup. I'm here to teach you Demonology. You can call me Kaira—

Just then, my demon familiar nudged me on the shoulder. "He's coming. I smeeeell him~keheHeheeHEEH!" He crackled a terrifying laughter.

I raised a brow, and asked, "Whose coming?"

"I'M SORRY I'M LATE, I'M…!"

Just when I was about to turn around, a huge force collided into me, knocking me off from my feet. As I was falling, my hand shot out in reflex to grab that person's arm, bringing him down with me.

"Whaaaa—

Everything happened so fast. As my head collided against the floor, lost consciousness for a moment, but quickly recovered about a minute or so. When my vision began to clear up, the first thing I saw were lips—they were trembling. Still in daze, my gaze wandered downwards to see his top few buttons of his shirt unbuttoned, which exposed a bit of his pale, but muscular chest.

"K-Kaira….?"

Almost immediately, I was broken out of my trance. When I glanced upwards, my eyes were met with a pair of beautify sapphire ones.

My heart stopped.

"Rin?!" His name left my lips in a gasp, and I grew panicked. Only now did I realise that I was lying flat on the ground with him on top of me. Like mine, his cheeks were flushed crimson in embarrassment. My head was trapped between both his arms, and he was straddling my hips. With him frozen in place, I couldn't escape.

Seconds felt like minutes then. I couldn't take my eyes away from him—it was as if his very existence was drawing me towards him. My heart fluttered when he leaned closer, his breath fanning my cheeks.

My eyes fluttered shut. He was about to—


	4. Chapter 4

_Seconds felt like minutes then. I couldn't take my eyes away from him—it was as if his very existence was drawing me towards him. My heart fluttered when he leaned closer, his breath fanning my cheeks._

 _My eyes fluttered shut. He was about to—_

"OKUMURA…! YOU DID THAT ON PURPOSE…!" I heard a boy shout, pushing Rin off of me and grabbing him by the collar.

My whole body felt numb, as I watched the scene unfold.

Rin was lifted off the ground by a larger, delinquent-looking boy. The boy growled, slamming him against the blackboard. "What were you trying to do to our teacher….?! HUH?!" He shouted at the male.

"B-BON! WHAT ARE Y—YOU….!"

"Don't call me that! Why are you always causing trouble for everyone?! Why can't you take everything seriously for once?!"

"What are you talking about?! I am serious—

"Hey guys! Calm down….! It's alright!" I shouted, getting up to my feet. Quickly, I got between the boys and tried to break up the fight. "It was just an accident."

"Accident, yeah right." The delinquent snorted, narrowing his eyes dangerously at Rin.

The other male was about to fight back when I stood between them. Crossing my arms and raising my voice, I ordered "Stop fighting…! Go back to your seats now! Or I'll make you clean up this class room!"

Immediately, everyone's face went pale, including the girls'. Reluctantly, both of them did as they were told—well, not before sending a death glare to each other and huffing as they went. Rin sat alone at the back while the other boy returned to his group of friends.

"Okay now, everyone. Shall we begin? Today I'm going to go through with you the different classes of demons. They are divided into a few classes and sub-classes. Some of them which—

* * *

I was grateful that I had no more lessons with them for the rest of the day. Throughout the whole lesson today, out of embarrassment, I couldn't look at Rin. He probably felt the same. This made things much more awkward than it already was. He was fully engrossed in his textbook, which was propped upright, shielding his face—trying to ignore me completely. After the class ended, he stormed out of the classroom without saying a word.

After splashing my face with water, I looked into the bathroom mirror. There was still a light tint of pink on my cheeks. Overall, I looked like a flustered schoolgirl.

"What the hell am I doing?" Those words left my throat, as I buried my head in my palms. "I'm supposed to be a teacher for god's sake, Hell, I'm an Upper First Class exorcist…..I shouldn't be acting like this."

 _But in the first place…Why was Rin here?_

 _He can't possibly want to become an exorcist, right?_

 _There is no way the Vatican would allow the son of Satan to live if they found out about him…_

 _How did he even get into True Cross the first place? If my memory serves me right, Rin wasn't the best in his studies...and I doubt he knew much about exorcists in the first place._

 _Someone was definitely pulling strings—and it was completely obvious who it was—_

"Samael!" I seethed, tugging my locks of hair. "I knew he was up to something…! He's scheming something again! I should have known! He was way too nice to me yesterday…!"

With all those thoughts swimming in my head, I had barely registered hearing my familiar call my name.

"Kaira~!" Inugami called, nibbling my ear.

"H-Hey stop that!" I hissed, making a shooing motion with my hand.

"It's important. I smell Satan's spawn outside. He's waiting for you, I think. KehehehHEEHhehehH"

Again, it feels as though my heart was about to leap out of my throat.

"Inugami…don't call him that…. But wait. W-Why is he waiting outside?"

"Seems like he's waiting for you to come out~Keh!"

"B-But why?"

"Awww…keehehHEehhhe…you look soooo cute when you're nervous, Kaira~ That was a nice show you put up this morning. I wonder what would have happened if he actually kissed youuu..? I might've gotten jealous and ripped out his throat," the demon said, crackling with laughter.

"S-Shut up. You idiot! Arghh….Let's go outside. You're coming with me, Inugami and you better not say anything!"

Indeed, like what Inugami said, Rin was waiting down the corridor. Leaning against the wall, his arms were crossed and his body was stiff. His eyes were rapidly darting left and right.

"Umm….hey," I began, unsure what to say.

Rin jumped, probably not noticing me before. "K-Kaira! H-Hey….!" His voice came out at a slightly higher pitch than usual. "C-Can we talk for a moment…?"

"Sure…I want to say something as well. Can we talk outside? Somewhere quiet, maybe…"

"Yeah, okay…"

We walked in silence, with him following me from behind—as if he was trying to keep his distance away from me. From time to time, I would glance back at him but quickly look away when he caught my gaze. Only now did I realise how much he has grown over the past few years. He was probably half a head taller than me now.

I remember him being so small in my arms that I could carry him and bring him for piggy back rides. Those were the days. He, along with Yukio would always beg me to take them to the park. Fujimoto, being the Paladin, was busy most of the time—so he'll have me take care of them whenever he's away. Unlike Rin, Yukio knew about demons from a young age—due to the demon wound he received from his brother. So when he found out that I was part demon, he became more detached from the both of us. This was the same even after he started his duties as an exorcist—he would avoid me, especially if we had missions together. But thankfully it was just one or two of them, considering we were of different ranks.

Yukio had become more and more independent as he grew older—always studying and reading books whenever he could. Because of his hard work, he had become a fine exorcist—and most likely a great doctor in the future.

Rin, on the other hand, was ignorant of the world of demons till now. Like Fujimoto, I thought it was best for him to live a normal life—at least while he could.

 _Who'd knew things would turn out like this?_

I'm his guardian now—not that I didn't want to be but….

 _What right do I have to be his guardian? I murdered his father. I made him and Yukio orphans…._

 _This wasn't right._

Once we got out of the building, I led him to the courtyard, which was devoid of students, considering it was late evening now and most of them had gone home by now. I stopped when we reached the school fountain.

"What was it did you want to talk about…?" I asked, looking at him now. My stomach felt even more uneasy than before.

As if embarrassed, he rubbed the back of his neck, his gaze stuck on the ground. "It's about today. I want to apologize to you more properly…I realised that what I did was impropriate! I'm really sorry!" He said, bowing quickly in apology.

I raised a brow. "Hey…It's no big deal. Accidents happen…"

"But still…."

"Look. I'm fine. So don't look so down about it," I said, trying to flash him a smile.

 **That's right.**

I was _trying_. There was an aching pain in my heart—I was still consumed with guilt after what I did to Fujimoto. Whenever I looked at Rin, this feeling would return.

 _I didn't deserve to be his teacher._

 _I didn't deserve to be his guardian._

"Right…." He trailed off, unsure what to say.

"Rin."

"Huh..?"

"I'm sorry….. for your dad…" Those words were caught in my throat. The smile I had before was replaced with a frown.

His reaction to my words were immediate—hurt flashed across is eyes. His trembling hands clenched the hem of his shirt. It was as if he was trying his best not to break down.

"….but it's not your fault," he said—it sounded a little forced.

I let out a bitter smile, and said, "That's what everyone keeps saying…But you can't look away from the truth. I killed Father Fujimoto with these hands—you saw them…I'm his murderer."

Rin was obviously trembling now.

Despite this, I continued. He needed to hear this. I have waited weeks to tell him this—there was no going back now. I unsheathed my sword and handed the hilt of it over to him.

Surprise was evident on his face, as well as confusion.

"W-Wait. What are you doing…?"

"Take it."

"B-But why—

"Why are you afraid? Aren't you the Son of Satan? " I asked in a threatening tone. Eyes narrowed dangerously into slits.

"…Don't call me that…!"

"But it's the truth. You can't look away from this…You're a demon. Just like me…"

Rin's scared expression quickly morphed to one of rage, his pupils slowly turning into slits. There was a flash of blue across his onyx eyes. "Call me what you want….but inside, I'm still human! And no one is going to change that…!"

"Tell me then…why did you choose to become an exorcist?"

"I'm going to defeat Satan!"

"Why…?"

"Because…."

"You want revenge, isn't it? You want avenge your dad. That's why you're trying so hard to become an exorcist…But let me tell you," I said, taking a step forward. "Satan didn't kill your dad. _I did_."

"Y-You…"

"So why are you holding back? Take my sword. Take it and drive it into my heart."

When he did nothing, I shoved the hilt into his hand, before taking a step back. "I've given you my sword as a form of my consent. No one would blame you for my death, so you shouldn't hesitate."

* * *

 **Rin's POV (3** **rd** **PERSON)**

 _Was this how she saw it?_

 _He chose to become an exorcist for revenge?_

No. She's wrong. That was not how she and dad brought him up. He would never let hatred consume his heart—he wasn't a demon. He was different!

"Y-You're wrong…! It's because I want to protect everyone. I won't let anyone die because of Satan! And that includes you…!" He shouted, stabbing the sword onto the ground and taking a step towards Kaira.

She jumped when he suddenly raised his voice and just then, he thought he saw a flicker of emotion in her eyes.

"B-But why…? I—

"Because…you raised me. You protected me all this while…! And I will never forget that!"

Just then, she pushed him away, snarling. "What do you know, Rin?! You don't even know how I'm really am…! I'm not who you think I am…! I'm a cruel, evil—

"Kaira," he cut me off, his hands grasping her shoulders.

"W-What are you doing…?!" She sounded frantic and at the same time, afraid. The complete opposite of the person she was seconds ago. He may not be the brightest person on the earth, but it was obvious she was genuine sorry and all the guilt was eating her alive. It hurts to see her like this.

"Idiot. We're both the same. We didn't choose to be born as demons. Appearances doesn't matter to me...! Like I said, I didn't choose to become an exorcist to kill. I chose to become an exorcist to protect people important to me….I know you long enough to know that you're a good person! And I want to protect you…!"

He noticed her bottom lip quivered. His hand patted her back, as he pulled her into a hug—which was very uncharacteristic of him. Usually he'd be embarrassed around girls, especially when it comes to physical contact. But it was different this time. He needed to set things right and tell her how he felt.

"These claws. They didn't kill my dad. _They saved him._ They _saved me_."

Her reaction was instantaneous. She tried to draw back, but he stopped her from doing so. Tears rolled down her cheeks as she screamed at him, "I don't understand! Why won't you hate me?! I did something unforgivable and yet…."

"I can never hate you."

"….what…?"

"When I was a kid, everyone hated and feared me—but not you. You were always there. You never judged me like everybody else…...I found that you're the only person that I could relate to, even till now…What had happened is all in the past now. I don't want our relationship to change."

The blush on his face intensified. He was never one to be forward.

"…Rin."

"…..so promise me…Kaira, that you'll stay by my side."

Her eyes were slightly reddish now from all the crying. Only now did Rin realise that he was still holding her wrist, which probably was bruised by now.

"Ah…! Sorry I hadn't realised! Does it hurt?!"

"Idiot." she said, with a small smile on her lips.

That little smile was enough to make Rin's heart flutter.


	5. Chapter 5

_Notes: Hey everyone! Sooo sorry for not updating such a long time! I've just finished my university exams a few weeks ago so I didn't manage to get much writing done then... :'( But on the bright side, it's summer break now! :3 I'm working on the next few chapters so expect me to update around next week! Thank you for the kind reviews and favorites! 3_

 **Chapter 5**

" _He forgave you, did he? How foolish…"A sweet feminine voice rang in my ears. "You never cease to amaze me, Kaira. Tell me…how do you do it? How do you manipulate others and lie without batting an eyelash?"_

 _Her words contrasted the tone of her voice—those words were full of disdain._

 _I searched for the source of the voice, but no avail. The voice seemed to echo throughout the infinite space I was in. Darkness obscured my vision, but from the sound of rustling leaves and the feeling of soft grass beneath my feet, I could tell that I was in a forest of some sort._

"… _.And now you're taking my place…,"she trailed off. It was barely above a whisper, but my demonic hearing picked it up. The voice certainly belonged to a young woman, which I didn't recognise. "You're taking my place and taking away what's most_ _ **precious**_ _to me."_

 _Her voice suddenly turned venomous. That shook me to the core. Out of sheer reflex, my hand flew to my hip, where my short swords usually were…_ _ **only to find out that they were gone.**_ _I grew panicked when I heard rustling of bushes behind me._

 _Gathering my courage, I spun around to face a sole figure. Beneath the tree was a woman dressed in a dark coat with a bright pink scarf[1]. She had long wavy dark hair which reached her hips. With her back turned towards me, I couldn't see her face. But what I did see were the beautiful white camellias by her feet. Bloomed in such a dark, dank place, I found them quite unusual—as though those flowers did not belong there._

" _I don't know what you're talking about," I said, trying to sound brave._

" _You know very well what I mean…Or have you forgotten…? My…has it been so long that you've forgotten what you've done to me….?!" The voice screeched into my ears. "I will never forgive you! I'll make sure you suffer for the rest of your life for what you've done! YOU WILL PAY FOR EVERYTHING—_

I woke up with a start, my heart pounding like crazy. Placing a hand over my chest, I tried to calm myself down, taking deep breaths. When I brushed my hair out of my face, only then did I realise that I was covered in cold sweat. Hell, my whole body was damp and my clothes were clinging to my skin.

 _Just what was this dream?_

Everything in that dream felt so real. Her voice sounded to close, as if she was just right in front of me. There was a sickening feeling in my stomach as though I was about to—

I clasped my hand over my mouth, hopping out of bed to dash to the bathroom. I fell to my knees, by the toilet bowl and vomited. It went on for quite a while but once I'm done, I felt much better—aside from the lingering taste of acid in my mouth.

With a frown, I looked at myself in the mirror. The dream I had was quite unsettling—almost as if it was a sign of bad omen.

"Who is that woman?" I asked myself, placing a palm on my face.

But most important of all, _why do I feel like I know her?_

* * *

"Good evening, Kaira-sensei."

"Good evening Bon, Shima, Konekomaru," I said with a forced smile.

"You look really tired. Are you alright, sensei?" Bon asked, with a raise of a brow.

"I am. Thanks for asking. I just didn't have much sleep last night—

I stopped short when I caught sight of a familiar half-demon at the corner of my eye. Rin was idly chatting with Shiemi by the hallway, a large grin plastered on his face. It's been a while since I have seen him laugh like this.

The blonde girl giggled excitedly, then talking like a bubbly school girl. They seemed so happy together. It didn't take long for me to put two and two together.

 _Wait. Are they dating?_

I shook my head.

 _Does it matter if they're seeing each other? Rin is a grown boy now. It was natural he would be interested in other girls his age._

 _It's none of my business to know who he is dating. But what's this strange feeling in my chest?_

"Kaira-sensei?"

A voice brought me back to reality. I let out a nervous laugh, saying, "Oh sorry, what were you saying, Bon?"

He let out a sigh. Knowing I hadn't been listening at all. Thankfully he said nothing about it. "You should take care of yourself more. Who'll teach us if your get sick?"

"Aww…are you worried?" I teased the boy, causing him to blush.

"Of course not! It—It's just that—I want to learn as much as possible and become a great exorcist…!" Bon blurted, running his hand through his thick locks of hair. His cheeks were starting to dye a deep shade of red.

Shima let out a laugh, clutching his stomach. "Looks like someone's embarrassed."

"I'M NOT!"

"Anyways, if you don't mind me asking. How old are you, sensei?" The pink haired boy asked with a wide grin, leaning closer towards me—a little _too_ close for comfort.

"Ummm….I'm eighteen," I lied. There was no way I'm telling them I'm a few centuries old.

"Score!" He suddenly said, elbowing Konekomaru who stared in shock. I did the same. Wiggling his eyebrows suggestively he whispered something to Bon. The said male's face grew even more heated. _"Hot and mature, that's how you like them, right Bon?"_

"Excuse me?"

"Ahh….it's nothing sempai—I mean sensei…!"

"Uhhhh okay…..if you say so…" I said, voice trailing off, feeling my own face heat up. "Anyways, I have to be going soon. I have a mission to attend to."

 _What was with teenage boys nowadays? Or rather, what is with their hormones?_

"What sort of mission?" Bon asked, curiously.

"Demon extermination," I said, placing my hands on my hips. "That's my speciality. There's just this really irritating pest that I have to take care of for Sama—I mean, Sir Pheles."

" _Where are you going?"_

I jumped when I heard a voice behind me. I spun around to meet a pair of deep blue irises. My heart nearly leapt out, due to the proximity. His face was just inches away from mine, which made me step back.

"Just downtown. It won't take too long. I'll get it done before our class—

"Let me come with you!" Rin said, face full of determination.

"WHAT?!" Bon was the first to react, glaring at the boy. "This is sensei's job! You can't just interfere!"

I casted a shocked glance at Rin. "Bon's right. I can't allow you to follow. It's too dangerous for you."

"But—

"I can't—

" _ **Always trying to protect him…trying to keep him safe. But little does he know, the only thing he should fear the most, is YOU…"  
**_

My blood suddenly ran cold.

It was the same voice from my dream. My eyes grew wide in realisation.

"Kaira-sensei?" It was Shima's voice that brought me back to reality. "You look like you've seen a ghost."

I glanced at Rin, wondering what those words meant. Without a doubt, that voice was referring to him.

"Did you hear her?" I asked Rin. Biting down on my bottom lip, I tried to calm myself down.

"Huh? What do you mean?" He asked, dumbfounded, looking around the hallway. "Who are you talking about…?"

My face paled considerably at his answer. He noticed this and grasped my wrist worriedly. "I'm taking you to the health office."

"I-It's fine, Rin…You should go to class…I can go there myself."

"It's not fine! Look at you! You're trembling…" With that said, he pulled me with him in a tow, leaving the rest of his classmates in time. Rin then turned to Shiemi and the guys, saying that he'll be back for class soon and asked them to tell Yukio that he would be late.

When we got to the health office, apparently we were the only ones there. The nurse was gone for lunch break and won't be back for half an hour. Even while we're there, he never let go of my hand, which I found very uncharacteristic of the young boy. He was never this forward. Before, he would cower at the sight of girls.

"What happened, Kaira?"He asked. His worried gaze was on me now. "Is it because of last night—or did I do something wrong—or…"

"Rin," I said, the corners of my lips lifted a little. He was such a sweetheart. "You did nothing wrong. Don't worry so much…"

"Then tell me what's wrong. I won't know what's wrong unless you tell me."

I thought about for a moment. I didn't want to worry him too much so I thought it was best if I didn't tell him all of it. "I had a bad dream last night, that's all…I'm just a little exhausted."

"Then you should rest here. You should take the day off."

"You know I can't do that. Our class is behind schedule," I said, whacking the boy playfully on the shoulder. He let out tooth grin in response. "And I really reaaaally have to go for the mission. Or else Mephisto will cut my pay."

As if sensing the dark clouds above my head, he squeezed my palms reassuringly. "Come on! Let's have a nap on the roof top! There would be no one there at this time of the day!"

"But—

"Let's go!" His grip on my arm tightened and he literally dragged me up the stairs all the way to the top.

When we reached the roof, we were both panting heavily. It was nearly mid-day and the warm sun was shining right above us. A soft breeze caressed my face, blowing tresses of my hair all over. I pursed my lips, grumbling a little about how I would have to fix my hair later. This earned a chuckle from Rin.

He led me to a shaded area, where we laid down and watched the clouds.

"You've haven't changed much," he began. "You're still the same. I'm glad."

"Oh really? I hadn't realised…"

"Yeah…Hey, Kaira…can I ask you something?"

"What is it?"

"I used to think I knew you very well since you've been with me since I was a kid. But I guess I was wrong. Ever since the day I found out about demons, I realised that you weren't the person I thought you were—I didn't know anything about you at all….."

"Does it bother you that I'm a demon?"

"O-Of course not!" he said, slightly embarrassed. "To be honest…when I found out that I was the Son of Satan…I was terrified. I was scared that people around me would start hating me and shun me…...It is selfish of me to say this, but…I'm actually very glad that you were the same as me—I'm glad that I'm not alone."

"You aren't alone, Rin. I promised you that I'll always be by your side, didn't I? So you'll never be alone on this."

"….you're far too kind, you know that?" He said with a chuckle. "By the way, you've never told me why you chose to become an exorcist."

A sheepish laugh escaped my throat. "Well, my reason is completely different from yours," I said, falling into deep thought. "I became an exorcist because of Father Fujimoto…He found me wounded in the forest. Surprisingly he didn't kill me. Instead, he brought me back to the monastery and nursed me back to health. He allowed me to stay even after I was fully recovered and offered to become my mentor. I, along with Shura trained with him until we got our Meisters. Yukio joined us soon after when he was old enough.[2]"

"I see…so I was the only one oblivious to everything happening around me…" He said, down casted.

"Rin." His ears twitched when I called his name. I reprimanded him, "All Father Fujimoto wanted was for you to live a normal life. So did Yukio and me. Do you regret knowing about everything?"

"To be honest…sometimes I wished that all of this was a dream—I wished that none of this ever happened and dad was still with us…I still wake up in the morning sometimes thinking I was still in my old bed, at the monastery…and Dad would burst into my room, ripping my covers off and making me cook breakfast. He would shout at me and call me 'lazy' all the time. In return, would often argue with him for making me do chores or run errands all the time….if only I knew earlier—how hard he was trying to protect us and everyone else…I would have been much nicer to the old man," He confessed, eyes fluttering shut. A single tear slid don his cheek. "But holding onto the past won't change anything…..No matter how much I try. There's no way I can bring him back…I can't lie to myself anymore. I don't regret knowing the truth because I'm going to use my flames to become stronger and defeat Satan."

He sat up, looking at me over his shoulder with moist eyes. There was a small genuine smile on his face as he extended his hand towards me.

" _So please teach me how to use my flames…..I want to become stronger."_

* * *

 _[1] If you've watched the anime over and over again like me, you'd probably already guessed who she is. :3 For those who don't, just follow this story and you'll get it eventually in the later chapters. Anyways no spoilers for you guys :) You'll have to read more to find out why she's mad with Kaira-or why Kaira is dreaming about her to begin with~_

 _[2] Because of Kaira's demon genes, she is about few centuries old but doesn't look much older than Rin. Just like how Amaimon and Mephisto are over a thousand years old. So Shura met Kaira when she was still a child, just after Fujimoto rescued her._

 _Anyways, hope you liked this chapter!_


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